/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/blockcancel.internal.h"
#include "libc/calls/struct/rusage.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/errno.h"
#include "libc/stdio/internal.h"

/**
 * Closes stream created by popen().
 *
 * This function is not a cancelation point and does not raise EINTR. It
 * is undefined behavior to pass a stream not created by popen(). If the
 * stream had a write error while flushing then `errno` may be clobbered
 *
 * @return wait status of subprocess, or -1 w/ wait errno
 * @raise ECHILD if child pid didn't exist
 */
int pclose(FILE *f) {

  // "If the argument stream to pclose() is not a pointer to a stream
  //  created by popen(), the result of pclose() is undefined."
  //                                —Quoth POSIX.1-2024
  int pid = f->pid;
  unassert(pid > 0);

  int ws;
  BLOCK_CANCELATION;
  fclose(f);
  for (;;) {
    int e = errno;
    int rc = wait4(pid, &ws, 0, 0);
    if (rc == -1) {
      if (errno == EINTR) {
        errno = e;
        continue;
      }
      ws = -1;
    }
    break;
  }
  ALLOW_CANCELATION;

  return ws;
}
